Since the world did not end, you should probably think twice about those motion control shoes….

WE can all agree that there is a time and a place for motion control shoes. For people with chronic ankle sprains or lateral instability (ie, an incompetent lateral compartment; peroneus longus, brevis or tertius), it is neither the time, nor the place.

The lateral ankle is stabilized by both static (ligaments: above lower left) and dynamic (muscles above, lower right) elements. This is often called “the lateral stabilizing complex” The lateral ankle (ie the lateral malleolus) also projects more inferiorly than the medial. This means that when push comes to shove, the ankle is more likely to invert (or go medially) than evert (or go laterally). What protects it? The static component consist of three main ligaments (seen above) the posterior and anterior talofibular ligaments and the calcaneofibular ligaments. The dynamic components are the peroneii muscles. These muscles not only stabilize but also exert an eversion (brings the bottom of the foot to the outside) force on the ankle.

So what you say?

according to one study we found “Using an in-shoe plantar pressure system, chronic ankle instability subjects had greater plantar pressures and forces in the lateral foot compared to controls during jogging.”

Hmmm. Remember the midsole? (If not click here and here for a review) Motion control shoes are medially posted. That means they provide more support medially or  have a tendency to tip the foot laterally. SO, motion control shoes shift forces laterally.

A person with chronic ankle instability has weakness of either the static, dynamic, or both components of the lateral stabilizing complex.

bottom line? make sure folks have a competent lateral stabilizing complex and if they don’t, you may want to think twice about using a motion control shoe.

Ivo and Shawn. Increasing your shoe geekiness coefficient on daily basis!                                                                                                                                                    

Foot Ankle Int. 2011 Nov;32(11):1075-80. Increased in-shoe lateral plantar pressures with chronic ankle instability. Schmidt H, Sauer LD, Lee SY, Saliba S, Hertel J. Source University of Virginia, 2270 Ivy Road, Box 800232, Charlottesville, VA 22903, USA.

Abstract BACKGROUND:

Previous plantar pressure research found increased loads and slower loading response on the lateral aspect of the foot during gait with chronic ankle instability compared to healthy controls. The studies had subjects walking barefoot over a pressure mat and results have not been confirmed with an in-shoe plantar pressure system. Our purpose was to report in-shoe plantar pressure measures for chronic ankle instability subjects compared to healthy controls.

METHODS:

Forty-nine subjects volunteered (25 healthy controls, 24 chronic ankle instability) for this case-control study. Subjects jogged continuously on a treadmill at 2.68 m/s (6.0 mph) while three trials of ten consecutive steps were recorded. Peak pressure, time-to-peak pressure, pressure-time integral, maximum force, time-to-maximum force, and force-time integral were assessed in nine regions of the foot with the Pedar-x in-shoe plantar pressure system (Novel, Munich, Germany).

RESULTS:

Chronic ankle instability subjects demonstrated a slower loading response in the lateral rearfoot indicated by a longer time-to-peak pressure (16.5% +/- 10.1, p = 0.001) and time-to-maximum force (16.8% +/- 11.3, p = 0.001) compared to controls (6.5% +/- 3.7 and 6.6% +/- 5.5, respectively). In the lateral midfoot, ankle instability subjects demonstrated significantly greater maximum force (318.8 N +/- 174.5, p = 0.008) and peak pressure (211.4 kPa +/- 57.7, p = 0.008) compared to controls (191.6 N +/- 74.5 and 161.3 kPa +/- 54.7). Additionally, ankle instability subjects demonstrated significantly higher force-time integral (44.1 N/s +/- 27.3, p = 0.005) and pressure-time integral (35.0 kPa/s +/- 12.0, p = 0.005) compared to controls (23.3 N/s +/- 10.9 and 24.5 kPa/s +/- 9.5). In the lateral forefoot, ankle instability subjects demonstrated significantly greater maximum force (239.9N +/- 81.2, p = 0.004), force-time integral (37.0 N/s +/- 14.9, p = 0.003), and time-to-peak pressure (51.1% +/- 10.9, p = 0.007) compared to controls (170.6 N +/- 49.3, 24.3 N/s +/- 7.2 and 43.8% +/- 4.3).

CONCLUSION:

Using an in-shoe plantar pressure system, chronic ankle instability subjects had greater plantar pressures and forces in the lateral foot compared to controls during jogging.

CLINICAL RELEVANCE:

These findings may have implications in the etiology and treatment of chronic ankle instability.

 

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